Medical image processing apparatus

ABSTRACT

A medical image processing apparatus comprises a structure identifying part, an image generator, and a display controller. The structure identifying part identifies a tubular structure inside a subject and a core line in the axial direction of the tubular structure based on medical image data. The image generator generates medical images when viewing a predetermined observation object from a desired view point position inside the tubular structure. The display controller causes the display to display medical images. Furthermore, at each timing, the image generator identifies view point position at which the relative distance between the position of the observation object and the view point position becomes even among each of the timings, and generates a medical image from the view point position for each timing. Moreover, the display controller causes the display to display a plurality of the medical images generated for each of the timings in chronological order.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2012-038712, filed on Feb. 24, 2012; theentire contents of which are incorporated herein by reference.

FIELD

The embodiment relates to displaying medical images based on medicaldata obtained using a medical imaging apparatus.

BACKGROUND

Medical image processing apparatuses exist for displayingthree-dimensional image data collected by medical image diagnosticapparatuses. The medical image diagnostic apparatus herein includes anX-ray Computer tomography (CT) apparatus or Magnetic resonance Imaging(MRI) apparatus, X-ray diagnostic apparatus, ultrasound diagnosticapparatus, etc.

(Virtual Endoscopy: VE) is one method of displaying medical images basedon three-dimensional image data obtained using such a medical imagediagnostic apparatus.

VE is capable of displaying VE images in which an object located closeto a viewpoint is displayed larger while an object located far from theviewpoint is displayed smaller. Furthermore, because VE is capable ofarbitrarily setting the position or the direction of the viewpoint,regions impossible to be observed using an endoscope may also aredisplayed. In general, VE displays images by automatically shifting theviewpoint from the trajectory of a three-dimensional core line passingthe lumen of a tubular structure such as a preliminarily extracted largeintestine or esophagus. Such a method of displaying images is referredto as a fly through display. In an actual diagnosis, for example, anoperator makes a diagnosis by observing VE images being updated whilethe viewpoint is moving in the fly through display.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of the medical image processing apparatuspertaining to the present embodiment.

FIG. 2A is a sagittal image displaying the vicinity of the vocal cords.

FIG. 2B is a fly-through image displaying the vicinity of the vocalcords.

FIG. 3A is a sagittal image displaying the vicinity of the vocal cords.

FIG. 3B is a fly-through image displaying the vicinity of the vocalcords.

FIG. 4A is a drawing explaining one viewpoint position.

FIG. 4B is a drawing explaining a method of identifying one viewpointposition.

FIG. 5A is a flow chart showing a series of operations of the medicalimage processing apparatus pertaining to Embodiment 1.

FIG. 5B is a flow chart showing a series of operations of the medicalimage processing apparatus pertaining to Embodiment 2.

FIG. 6 is a drawing explaining a method of identifying one viewpointposition in the medical image processing apparatus pertaining toModified Example 2.

FIG. 7A is one example of medical images generated in the medical imageprocessing apparatus pertaining to Modified Example 2.

FIG. 7B is one example of medical images generated in the medical imageprocessing apparatus pertaining to Modified Example 2.

FIG. 8A is a drawing showing one example of display aspects in themedical image processing apparatus pertaining to Modified Example 2.

FIG. 8B is a drawing explaining one example of the display aspects inthe medical image processing apparatus pertaining to Modified Example 2.

FIG. 8C is a drawing explaining one example of the display aspects inthe medical image processing apparatus pertaining to Modified Example 2.

FIG. 8D is a drawing explaining one example of the display aspects inthe medical image processing apparatus pertaining to Modified Example 2.

FIG. 9A shows the outline of a heart and an aorta.

FIG. 9B is one example of a fly-through image displaying a valve of theheart.

FIG. 10A shows the outline of a heart and an aorta.

FIG. 10B is one example of a fly-through image displaying the inside ofthe aorta.

FIG. 11A is a drawing indicating the outline of a large intestine.

FIG. 11B is one example of a fly-through image displaying the inside ofthe large intestine.

FIG. 12A is a drawing indicating the outline of the large intestineexplaining a method of identifying one viewpoint position pertaining toModified Example 3.

FIG. 12B is one example of a fly-through image displaying the inside ofthe large intestine.

FIG. 13A explains a method of identifying one viewpoint positionpertaining to Modified Example 4.

FIG. 13B indicates the outline of a heart and an aorta for explainingthe method of identifying one viewpoint position pertaining to ModifiedExample 4.

FIG. 13C is one example of an image displaying the inside of the aorta.

DETAILED DESCRIPTION

The purpose of this embodiment is to provide a medical image processingapparatus capable of displaying an observation object at a predeterminedsize in a medical image, even when the position of the observationobject changes due to body movements.

In order to achieve the above purpose, the first aspect of thisembodiment is a medical image processing apparatus comprising an imagedata storage, a structure identifying part, an image generator, adisplay, and a display controller. The image data storage stores aplurality of medical image data obtained by imaging the inside of asubject at each point of a predetermined timing. The structureidentifying part identifies a tubular structure inside the subject and acore line in the axial direction of the tubular structure based on themedical image data. The image generator generates medical imagesrepresenting the inside of the tubular structure when viewing apredetermined observation object from a desired viewpoint positioninside the tubular structure. The display controller causes the displayto display the medical images. Furthermore, at each timing point, theimage generator identifies one viewpoint position at which the relativedistance between the position of the observation object and theviewpoint position becomes even among each timing point, and generates amedical image from the one viewpoint position for each timing point.Moreover, the display controller causes the display to display aplurality of the medical images generated at each timing point inchronological order.

Furthermore, the second aspect of this embodiment is a medical imageprocessing apparatus comprising image data storage, a structureidentifying part, an image generator, a display, and a displaycontroller. The image data storage stores a plurality of medical imagedata obtained by imaging the inside of a subject at each timing point.The structure identifying part identifies a tubular structure inside thesubject and a core line in the axial direction of the tubular structurebased on the medical image data. The image generator generates medicalimages representing the inside of the tubular structure when viewing apredetermined observation object from a desired viewpoint positioninside the tubular structure. The display controller causes the displayto display the medical images. Furthermore, the image generator receivesthe designated position of the observation object with regard to thefirst medical image data corresponding to a predetermined timing,identifies one viewpoint position corresponding to the relative distancein the first medical image data, and generates a medical image from theone viewpoint position as a standard medical image. Furthermore, withregard to the second medical image data corresponding to another timingdifferent from the predetermined timing, the image generator generatesmedical images while changing viewpoint positions such that the relativedistance between the position of the aforementioned observation objectand the aforementioned viewpoint position becomes even among each of theaforementioned timing points, and compares with the standard medicalimage so as to create a medical image substantially matching thestandard medical image as a medical image from one viewpoint position.Moreover, the display controller causes the display to sequentiallydisplay a plurality of medical images generated for each phase.

Embodiment 1

FIG. 1 describes the structure of the medical image processing apparatuspertaining to Embodiment 1. As shown in FIG. 1, the medical imageprocessing apparatus pertaining to the present embodiment includes imagedata storage 10, a structure extracting part 20, an image generator 30,an image storage 40, a display controller 50, and a U/I60. Furthermore,the structure extracting part 20 is configured to include a tubularstructure-extracting part 21 and a core line-extracting part 22.Moreover, the image generator 30 includes a viewpointposition-identifying part 31 and an image processor 32.

In the medical image processing apparatus pertaining to the presentembodiment, an observation object in three-dimensional image data isdesignated by an operator and a fly-through image in which theobservation object is displayed in a predetermined size is displayed asa motion image. Hereinafter, operations are described at each event byseparating the operations into “designation of an observation object”and “generation and display of a motion image.” First, operations in theevent of “designation of an observation object” are described. It shouldbe noted that the motion image in the event of “designation of anobservation object” is the same as in “generation and display of amotion image” unless otherwise specifically stated.

(Designation of an Observation Object)

The image data storage 10 is storage for storing three-dimensional imagedata (for example, volume data) of a plurality of timing points obtainedby imaging a subject in each examination by an imaging part 100. Theimaging part 100 is a medical imaging apparatus capable of obtainingthree-dimensional image data, for example, as with a CT, MRI, ultrasounddiagnostic apparatus, etc. It should be noted that hereinafter, thethree-dimensional image data is referred to as “medical image data.”Furthermore, hereinafter, medical image data is described as volume dataobtained by a CT.

First, the structure extracting part 20 reads medical image datacorresponding to a predetermined timing (for example, the earliesttiming) among medical image data of a plurality of timing pointscorresponding to a preliminarily designated examination (hereinafter,referred to as a “predetermined examination”). The structure extractingpart 20 outputs the read medical image data to the tubularstructure-extracting part 21.

The tubular structure-extracting part 21 receives the medical imagedata, extracts and identifies the tubular structure of a preliminarilydetermined tissue (that is, information indicating the structure such asthe position, the size, and the orientation of the tubular structure,esophagus, blood vessels, etc.) based on the voxel data in the medicalimage. The tubular structure-extracting part 21 outputs informationindicating the identified tubular structure to the core line-extractingpart 22.

The core line-extracting part 22 receives information indicating thetubular structure from the tubular structure-extracting part 21. Basedon this information, the core line-extracting part 22 extracts andidentifies the core line in the axial direction inside the lumen regionof the tubular structure. One method of extracting the core lineincludes a method in which three-dimensional thinning processing isapplied to binarization data from the extracted inside region of thelumen (for example, a thinning method or a skeletonization method).Thereby, information indicating the core line (that is, the position andthe orientation of the core line) is identified.

It should be noted that the structure extracting part 20 may also mapthe information indicating the tubular structure and the core line to apredetermined coordinate system. For example, the structure extractingpart 20 regards the direction in the core line as the z axis and theplane vertical to the z axis as the xy plane. By causing such anoperation, it becomes possible to identify the position inside thetubular structure. The coordinate system is one example but is notnecessarily limited to this coordinate system as long as the positioninside the tubular structure may be identified. Once the tubularstructure and the core line are identified, the structure extractingpart 20 outputs the information indicating the tubular structure and thecore line to the image generator 30 by linking with medical image datacorresponding to the information.

The image generator 30 receives the medical image data corresponding toa predetermined timing linked with the information indicating thetubular structure and the core line from the structure extracting part20. The image generator 30 causes a temporary storage (not illustrated)to store the medical image data. Thereby, it becomes possible for theviewpoint position-identifying part 31 and the image processor 32included in the image generator 30 to read the medical image data andall information linked to the data at a desired timing. Next, the imagegenerator 30 causes the image processor 32 to generate medical imagesbased on the received medical image data.

The image processor 32 receives instructions from the image generator 30and reads, from the temporary storage, medical image data correspondingto the predetermined timing and information indicating the tubularstructure and the core line corresponding to the data. Based on thisinformation, while changing the position of a camera (that is, theviewpoint position) in the core line, by subjecting the medical imagedata that has been read together to image processing, the imageprocessor 32 generates medical images representing the inside of thelumen of the tubular structure from each viewpoint position on the coreline. Thereby, while moving the viewpoint position along the core line,a fly-through image is generated presenting the inside of the lumencorresponding to the viewpoint position.

The image processor 32 outputs the generated fly-through image to thedisplay controller 50. The display controller 50 causes the display ofthe U/I60 to display the fly-through image received from the imageprocessor 32. The U/I60 is a user interface that works as a display andoperation part. Thereby, it becomes possible for the operator todesignate the position of an observation object inside the tubularstructure via the operation part while referring to the fly-throughimage that is being displayed on the display.

Herein, FIG. 2A and FIG. 2B are used as references. The medical imageD121 shown in FIG. 2A is a sagittal image in which the vicinity of thevocal cords of the head part of a subject is displayed. V11 in FIG. 2Aindicates a viewpoint and R1 indicates a core line. P11 indicates theposition of the viewpoint V11 (that is, a viewpoint position) and P12indicates the position of the vocal cords in FIG. 2A. Furthermore, P13indicates the position of the vocal cords at other timing points (FIG.3A), described later. Moreover, the medical image D122 shown in FIG. 2Bshows a fly-through image in the case of displaying the position P12from the viewpoint position P11 in FIG. 2A. Hereinafter, a case isdescribed in which the vocal cords displayed in the position P12 by theoperator is designated as an observation object. It should be noted thatalthough an example of displaying a fly-through image was described inorder to designate an observation object, the display aspect is notlimited to a fly-through image as long as the observation object can bedesignated. For example, the sagittal image shown in FIG. 2A or imagesfrom other angles may also be used.

The U/I60 outputs viewpoint information indicating the position (thatis, positional information) of the designated observation object(specifically, the position or the region within a tubular structure) tothe viewpoint position-identifying part 31 via the operation part. Theviewpoint position-identifying part 31 identifies coordinates indicatedby the information as the position of the observation object(hereinafter, referred to as the “object position”).

Based on the positional information of the object position, theviewpoint position-identifying part 31 identifies the viewpoint position(hereinafter, the identified viewpoint position is referred to as the“one viewpoint position”) for generating a fly-through image whenviewing the observation object (toward the observation object).Hereinafter, with reference to FIG. 4A, the method of identifying theone viewpoint position is described. FIG. 4A is a drawing describing theone viewpoint position. P12 in FIG. 4A indicates the object positioncorresponding to P12 in FIG. 2A. Moreover, R1 in FIG. 4A indicates thecore line corresponding to R1 in FIG. 2A. The viewpointposition-identifying part 31 identifies the core line R1 based oninformation indicating the core line that has been linked to medicalimage data corresponding to a designated object position.

Next, the viewpoint position-identifying part 31 identifies, as the oneviewpoint position P11, the position P11 separated from the objectposition P12 by a predetermined distance L (in other words, the positionP11 is set as the one viewpoint position P11) in a predetermineddirection (−z direction) in the core line R1. It should be noted thatthe distance L may be designated by the operator or may also bepreliminarily stored in the apparatus as a fixed value. Once the oneviewpoint position P11 is identified, the viewpoint position-identifyingpart 31 generates a medical image (that is, a fly-through image) whenviewing the object position P12 from the identified one viewpointposition P11, and causes the temporary storage to store the image. Itshould be noted that, hereinafter, this generated medical image of thedesignated object position P12 is sometimes referred to as a “standardmedical image.” Furthermore, V11 in FIG. 4A indicates a viewpoint V11when viewing the object position P12 from the one viewpoint positionP11, and a standard medical image is generated based on the viewpointV11. Moreover, medical image data which is the source of the generatedstandard medical image (generation source of the medical image in whichthe object position P12 is designated) is equivalent to “the firstmedical image data.”

(Generation and Display of Motion Images)

Next, the configuration pertaining to the generation and display ofmotion images is described. A medical image is generated by the medicalimage processing apparatus pertaining to the present embodiment whichidentifies the one viewpoint position with regard to medical image datacorresponding to another timing point different from the medical imagedata in which the object position P12 is designated (hereinafter, simplyreferred to as “another timing point”). Subsequently, a medical imagewhen viewing an observation object from the identified one viewpointposition is generated for each timing point. As described, the medicalimage processing apparatus causes the display of the U/I60 to display amotion image in which the observation object is always indicated as thesame size by displaying a generated medical image corresponding to eachtiming point in chronological order.

Incidentally, first, before describing the operation of eachconfiguration, the method of identifying one viewpoint positioncorresponding to another phase is described with reference to FIG. 2A,FIG. 2B, FIG. 3A, FIG. 3B, and FIG. 4B. The medical image D131 shown inFIG. 3A shows a sagittal image displaying the vicinity of the vocalcords, generated based on medical image data obtained in a phase that isdifferent from FIG. 2A. V11 in FIG. 3A indicates a viewpoint arranged atthe same position as in FIG. 2A while R1 indicates the core line. P11indicates the position of the viewpoint V11 (that is, the viewpointposition) while P13 indicates the position of the vocal cords in FIG.3A. It should be noted that P13 in FIG. 2A and FIG. 2B corresponds tothe position P13 in FIG. 3A. Furthermore, P12 corresponds to theposition P12 of the vocal cords in FIG. 2A and FIG. 2B. The medicalimage D132 shown in FIG. 3B represents a fly-through image of a case inwhich the position P13 is displayed from the viewpoint position P11 inFIG. 3A (in other words, a case in which the position P13 is displayedas the one viewpoint position P11). As is clear by comparing thepositions P12 and P13 of the vocal cords in FIG. 2A, FIG. 2B, FIG. 3A,and FIG. 3B, the tissue inside the subject is elongated/shrunk anddeformed due to body movements and sometimes the position (position onthe coordinates) is changed.

Herein, FIG. 4B is used as a reference. FIG. 4B is a drawing describinga method of identifying the one viewpoint position and indicates thestate of another phase different from the phase in which the standardmedical image is generated. V11 in FIG. 4B indicates the viewpoint atwhich the standard medical image is generated while P11 indicates theviewpoint position of the viewpoint V11. Furthermore, P12 indicates theobject position in a phase in which the standard medical image isgenerated while P13 indicates the object position in the phase.Moreover, L′ indicates the distance along the core line R1 from theviewpoint position P11 to the position P13, with the distance L′different from the distance L from the viewpoint position P11 to theposition P12.

As described previously, the position of the observation objectsometimes varies depending on the phase due to body movements.Therefore, when a medical image is generated, based on the viewpoint V11that is fixed at the same viewpoint position P11 among each of thephases, as shown in FIG. 2B and FIG. 3B, due to the distance differencefrom the one viewpoint position to the object position (L′≠L), theobservation object is displayed in different sizes among the phases.Therefore, when an observation object (for example, vocal cords) isdisplayed from the same viewpoint V11 in a plurality of phases, as shownin FIG. 2B and FIG. 3B, because the size of the observation object in amedical image changes in the phases due to the distance difference,sometimes the movement of the observation object itself becomesdifficult to observe.

Incidentally, with regard to medical image data corresponding to otherphases different from the medical image data in which the objectposition P12 is designated, the medical image processing apparatuspertaining to the present embodiment identifies the one viewpointposition such that the distance between the object position and the oneviewpoint position becomes equal to the distance in the case of astandard medical image. Specifically, as shown in FIG. 4B, the positionP14 of the distance L is identified, as one viewpoint position, alongthe core line from the object position P13. The viewpoint V14 indicatesthe viewpoint for displaying the object position P13 from the oneviewpoint position P14. As described, in the medical image processingapparatus pertaining to the present embodiment, with regard to medicalimage data corresponding to another phase, the one viewpoint positionP14 is identified such that the distance along the core line from theobject position P13 becomes equal to the distance L in the case when astandard medical image is generated. As described, by identifying theone viewpoint position P14 in a plurality of phases and generating amedical image in which the object position P13 from the one viewpointposition P14 is displayed, it becomes possible to display an observationobject (for example, vocal cords) always in the same size among aplurality of phases.

Next, the operations of each configuration are described focusing on theprocess related to identifying the one viewpoint position with respectto medical image data of another phase.

When a standard medical image is generated, the image generator 30instructs the structure extracting part 20 to identify a tubularstructure and a core line in the same examination as medical image datacorresponding to the standard medical image with regard to medical imagedata obtained in another phase different from the aforementioned data.Once these instructions are received, the structure extracting part 20reads medical image data corresponding to another phase from the imagedata storage 10, and causes the tubular structure-extracting part 21 andthe core line-extracting part 22 to identify the tubular structure andthe core line in the medical image data. Once the tubular structure andthe core line are identified, the structure extracting part 20 outputsinformation indicating the tubular structure and the core line to theimage generator 30 by linking with medical image data corresponding tothe information. In this way, with regard to the medical image datacorresponding to all phases in the examination, the structure extractingpart 20 identifies the tubular structure and the core line, and outputsthe information to the image generator 30 by linking with thecorresponding medical image data.

The image generator 30 consecutively receives medical image datacorresponding to the other phase to which information indicating thetubular structure and the core line has been linked from the structureextracting part 20. The image generator 30 outputs the information andthe medical image data to the image processor 32.

When the information indicating the tubular structure and the core lineas well as the medical image data is received, the image processor 32consecutively generates medical images (that is, fly-through images)when viewing the inside of the tubular structure from the viewpointwhile changing the position of the viewpoint along the core line andoutputs the medical images to the viewpoint position-identifying part31.

The viewpoint-identifying part 31 receives medical images correspondingto each viewpoint on the core line from the image processor 32. Theviewpoint position-identifying part 31 compares the received medicalimages to a standard medical image that has been temporarily stored inthe storage. Then, the viewpoint position-identifying part 31 detects anarea that has characteristics in its form such as irregularities(hereinafter, referred to as “form characteristics) with regard to eachof the medical images, making it possible to verify whether the formcharacteristics match between two medical images. As described, theviewpoint position-identifying part 31 identifies a medical imagematching the standard medical image from medical images corresponding toeach viewpoint transmitted from the image processor 32. In other words,the viewpoint position-identifying part 31 ends up identifying, in eachphase, a medical image having a distance L between an object positionand the one viewpoint position which is an equivalent distance L for thecase of standard medical images. As described, by identifying a medicalimage from a plurality of medical images, a medical image is identifiedin which the size of the observation object displayed in the medicalimage becomes the same size as the observation object displayed in thestandard medical image for each phase.

With regard to the standard medical image and each medical image foreach phase, by linking information indicating the phase corresponding tothe medical image data of the generation source, the viewpointposition-identifying part 31 causes the image storage 40 to store thisinformation. The image storage 40 is storage for storing medical images.As described, with regard to medical image data in a plurality of phasescorresponding to a predetermined examination, a series of medical imagesare generated and stored in the image storage 40.

The display controller 50 reads the series of medical imagescorresponding to a predetermined examination from the image storage 40.The display controller 50 refers to information indicating the phaseincidental to each read medical image and generates a motion image byarranging a series of medical images according to the order of thephases. The display controller 50 causes the display of the U/I60 todisplay the generated motion images.

Next, the series of operations of the medical image processing apparatuspertaining to the present embodiment are described with reference toFIG. 5A. FIG. 5A is a flow chart showing the series of operations of themedical image processing apparatus pertaining to the present embodiment.

(Step S11)

First, the structure extracting part 20 reads medical image datacorresponding to a predetermined phase (for example, the earliest phase)from among medical image data of a plurality of phases corresponding toa predetermined examination. The structure extracting part 20 outputsthe read medical image data to the tubular structure-extracting part 21.

The tubular structure-extracting part 21 receives the medical imagedata, analyses the voxel data in the medical image data, and extracts atubular structure (that is, information indicating the structure such asthe position of the tubular structure, the size, and the orientation) ofa preliminarily determined tissue such as the esophagus, blood vessels,etc. The tubular structure-extracting part 21 outputs the informationindicating the extracted tubular structure to the core line-extractingpart 22.

The core line-extracting part 22 receives the information indicating thetubular structure from the tubular structure-extracting part 21. Basedon this information, the core line-extracting part 22 extracts a coreline in the axial direction in the lumen region of the tubularstructure. Once the tubular structure and the core line are extracted,the structure extracting part 20 outputs the information indicating thetubular structure and the core line as well as medical image datacorresponding to this information to the image generator 30.

The image generator 30 receives medical image data corresponding to thepredetermined phase to which the information indicating the tubularstructure and the core line is linked from the structure extracting part20. The image generator 30 causes the temporary storage (notillustrated) to display this medical image data. Thereby, it becomespossible for the viewpoint position-identifying part 31 and the imageprocessor 32 included in the image generator 30 to read the medicalimage data and each piece of information linked to the medical imagedata at a desired timing. Next, the image generator 30 causes the imageprocessor 32 to generate a medical image based on the received medicalimage data.

The image processor 32 receives instructions from the image generator 30and reads medical image data corresponding to a predetermined phase andinformation indicating a tubular structure and a core line correspondingto the data from the temporary storage. Based on the information, whilechanging the position of a camera (that is, the viewpoint position)along the core line, the image processor 32 generates a medical imagerepresenting the inside of the lumen in a tubular structure from eachviewpoint position on the core line by subjecting the medical image datathat has been read together with image processing. Thereby, by movingthe viewpoint position along the core line, a fly-through image isgenerated presenting the inside of the lumen corresponding to theviewpoint position.

The image processor 32 outputs the generated fly-through image to thedisplay controller 50. The display controller 50 causes the display ofthe U/I60 to display the fly-through image received from the imageprocessor 32. The U/I60 is a user interface having roles as a displayand an operation part. Thereby, it becomes possible to designate theposition of an observation object inside the tubular structure via theoperation part while using the fly-through image displayed on thedisplay as a reference.

(Step S12)

The U/I60 outputs viewpoint information (that is, positionalinformation) indicating the position (specifically, the position orregion inside the tubular structure) of an observation object designatedvia the operation part to the viewpoint position-identifying part 31.The viewpoint position-identifying part 31 identifies the coordinatesindicated by the information as the object position.

The viewpoint position-identifying part 31 identifies one viewpointposition for generating a fly-through image when viewing the observationobject, based on the positional information of the object position.Herein, FIG. 4A is used as a reference. The viewpointposition-identifying part 31 identifies the core line R1 based oninformation indicating a core line linked to medical image datacorresponding to the designated object position viewpoint.

Next, the viewpoint position-identifying part 31 identifies theviewpoint of a position P11 separated from the object position P12 by apredetermined distance L in a predetermined direction (−z direction)along the core line R1 as the one viewpoint position. When the oneviewpoint position P11 is identified, the viewpoint position-identifyingpart 31 generates a medical image (that is, a standard medical image)when viewing the object position P12 from the identified one viewpointposition P11 and causes the temporary storage to store the medicalimage. Furthermore, V11 in FIG. 4A indicates the viewpoint V11 whenviewing the object position P12 from the one viewpoint position P11 andthe standard medical image is generated based on the viewpoint V11.

(Step S13)

When the standard medical image is generated, the image generator 30instructs the structure extracting part 20 to identify a tubularstructure and a core line in the same examination as in the examinationin which medical image data corresponding to the standard medical imagehas been obtained but with regard to medical image data obtained inother phases different from the aforementioned data. Once theseinstructions are received, the structure extracting part 20 readsmedical image data corresponding to the other phases from the image datastorage 10, and causes the tubular structure-extracting part 21 and thecore line-extracting part 22 to extract the tubular structure and thecore line in the medical image data. Once the tubular structure and thecore line are extracted, the structure extracting part 20 outputsinformation indicating the tubular structure to the image generator 30by linking the information to the medical image data corresponding tothe information. In this way, with regard to the medical image datacorresponding to all phases in the examination, the structure extractingpart 20 extracts the tubular structure and the core line, and outputsthe information to the image generator 30 by linking the information tothe corresponding medical image data.

(Step S14)

The image generator 30 receives medical image data corresponding to theother phases and information indicating the tubular structure and thecore line corresponding to the data from the structure extracting part20. The image generator 30 outputs the information and the medical imagedata to the image processor 32.

When the information indicating the tubular structure and the core lineas well as the medical image data are received, the image processor 32consecutively generates medical images when viewing the inside of thetubular structure from the viewpoint while changing the position of theviewpoint along the core line and outputs the medical images to theviewpoint position-identifying part 31.

(Step S15)

The viewpoint position-identifying part 31 receives a medical imagecorresponding to each viewpoint on the core line from the imageprocessor 32. The viewpoint position-identifying part 31 compares thereceived medical images to a standard medical image temporarily storedin the storage. Then, the viewpoint position-identifying part 31 detectsform characteristics with regard to each of the medical images, makingit possible to confirm if there is any matching of the formcharacteristics between the two medical images.

(Step S16)

If the generated medical image does not match the standard medical image(Step S17, N), a medical image is generated again by changing theposition of the viewpoint, and the medical image and the standardmedical image are compared.

(Step S17)

If the generated medical image matches the standard medical image (StepS17, Y), the medical image is linked to information indicating the phasecorresponding to the medical image data of the generation source andstored in the image storage 40. As described, by identifying a medicalimage, from a plurality of medical images, a medical image in which thesize of the observation object displayed on the medical image is thesame size as the observation object displayed in the standard medicalimage (that is, the distance L between an object position and the oneviewpoint position becomes equal to the case of a standard medicalimage) is identified for each phase and stored in the medical imagestorage 40.

(Step S18)

If a medical image matching the standard medical image is not identifiedwith regard to the entire phases (Step S18, N), the image generator 30instructs the structure extracting part 20 to identify a tubularstructure and a core line with regard to medical image data of thefollowing phase. As described, the viewpoint position-identifying part31 identifies a medical image that matches the standard medical imagewith regard to each phase among medical images corresponding to each ofthe viewpoints transmitted from the image processor 32.

(Step S19)

Once the medical images matching the standard medical image are storedin the image storage 40 with regard to all phases (Step S18, Y), thedisplay controller 50 reads a series of the medical images (that is, aseries of medical images corresponding to a predetermined examination)from the image storage 40. The display controller 50 uses informationindicating a phase incidental to each of the read medical images andgenerates a motion image by arranging these series of medical images inthe order of the phases. The display controller 50 causes the display ofthe U/I60 to display the generated motion image.

In the above, a one viewpoint position P11 (specifically, a medicalimage from the one viewpoint position P11) separated from the objectposition P12 by a predetermined distance L was identified based on afly-through image with regard to other phases; however, the method isnot limited as long as the object position P12 or the one viewpointposition P11 may be identified. For example, the identification may alsobe made based on sagittal images such as those shown in FIG. 2A or FIG.3A or images from another direction, or the identification may also bemade by detecting and comparing form characteristics from informationindicating a tubular structure corresponding to each phase.

It should be noted that an example in which the vocal cords in thebronchial tube was an observation object was described in the above butthe application is also possible with the heart, blood vessels such asthe aorta, and the intestines (large intestine or small intestine). Thisis the same with regard to other embodiments and modified examplesdescribed hereinafter. Hereafter, a specific example is described in theapplication to the heart, blood vessels, and intestines.

When applied to the heart, for example, a case exists in which a valveof the heart is the observation object. For example, FIG. 9A and FIG. 9Bindicate a case in which a valve of the heart is an observation object.FIG. 9A is a drawing showing the outline of the heart and the aorta. Inthe example shown in FIG. 9A, a tubular structure comprising the leftatrium, left ventricle, and the aorta has been extracted wherein R31indicates the core line of the tubular structure. The position P32 inFIG. 9A indicates the position of the valve between the left ventricleand the aorta, while the position P32 is identified as an observationposition. Furthermore, in FIG. 9A, a position separated from the objectposition P32 by the distance L onto the aorta side along the core lineR31 is identified as the one viewpoint position P31, while the viewpointV31 is set so as to view the object position P32 from the position. FIG.9B is one example of a medical image D321 (fly-through image) whenviewing the object position P32 from the viewpoint V31. P32 in FIG. 9Bcorresponds to the object position P32 in FIG. 9A.

Furthermore, when applied to the blood vessels, for example, cases inwhich a tumor in the blood vessels, stricture, and joints in the bloodvessels may be cited as observation objects. For example, FIG. 10A andFIG. 10B show cases of the application to an aorta, in which a portionof the joint of the aorta is an observation object. FIG. 10A is adrawing showing an outline of a heart and an aorta. In the example shownin FIG. 10A, a tubular structure comprising the left atrium, leftventricle, and aorta has been extracted while R41 indicates a core lineof the tubular structure. The position P42 in FIG. 10A shows theposition of a joint at which the aorta splits while the position P42 isidentified as the object position. Moreover, in FIG. 10A, the positionseparated from the object position P42 by the distance L onto theupstream side along the core line R41 is identified as the one viewpointposition P41 and, from this position, a viewpoint V41 is set so as toview the object position P42. FIG. 10B is one example of a medical imageD421 (fly-through image) when viewing the object position P42 from theviewpoint V41. P42 in FIG. 10B corresponds to the object position P42 inFIG. 10A.

In the case of an application to the intestine, for example, exemplarycases in which folds formed on the inner wall of the intestine or atumor developed within the intestine may be cited as observationobjects. For example, FIG. 11A and FIG. 11B show an applied case to alarge intestine, and a part within the large intestine (for example, theportion where the tumor has developed) is an observation object. FIG.11A is a drawing showing the outline of the large intestine. In theexample shown in FIG. 11A, the large intestine is extracted as a tubularstructure, while R51 indicates the core line of the tubular structure.The position P52 in FIG. 11A indicates the part within the largeintestine (for example, the portion where a tumor has developed), whilethe position P52 is identified as an object position. Furthermore, inFIG. 11A, a position separated from the object position P52 by thedistance L on the upstream side along the core line R51 is identified asone viewpoint position P51, and the viewpoint V51 is set so as to viewthe object position P52 from the position. FIG. 11B is one example of amedical image D521 (fly-through image) when viewing the object positionP52 from the viewpoint V51. P52 in FIG. 11B corresponds to the objectposition P52 in FIG. 11A.

As described, in the medical image processing apparatus pertaining tothe present embodiment, a medical image matching a standard medicalimage is identified with regard to each phase. In other words, themedical image processing apparatus identifies the one viewpoint positionregarding medical image data corresponding to each phase such that thedistance L between the object position P12 (or P13) and one viewpointP11 becomes equal among each of the phases and generates a medical image(that is, a fly-through image). Thereafter, the medical image processingapparatus generates and displays a motion image by arranging a series ofgenerated medical images in the order of the phases. Thereby, in eachphase, because the distance between the one viewpoint position and anobject position is evenly maintained, even if the position of theobservation object changes due to body movements, the observation objectis displayed in a predetermined size in the medical image, making itpossible to display the observation object in the motion image whilemaintaining the observation object in a predetermined size.

Modified Example 1

In Embodiment 1, an object position is designated only with regard to apredetermined phase; however, the object position may also be designatedwith regard to all phases. In Modified Example 1, operations in thiscase are described focusing on areas that are different from Embodiment1.

The structure extracting part 20 consecutively reads each piece ofmedical image data of a plurality of phases corresponding to apredetermined examination, and instructs the tubularstructure-extracting part 21 as well as the core line extracting part 22to identify a tubular structure and a core line with respect to the readmedical image data. The extracting method of the tubular structure andthe core line with respect to the each medical image data is the same asEmbodiment 1. Once the tubular structure and the core line areextracted, the structure extracting part 20 links information indicatingthe tubular structure as well as the core line to medical image datacorresponding to the information and outputs the information to theimage generator 30. As described, with regard to the series of medicalimage data corresponding to the predetermined examination, the structureextracting part 20 extracts the tubular structure and the core line,links the information, and outputs the information to the imagegenerator 30.

The image generator 30 receives from the structure extracting part 20 aseries of medical image data corresponding to the predeterminedexamination and the information indicating the tubular structure as wellas the core line corresponding to the data. The image generator 30 linksthe information and the medical image data received at the same time andcauses the temporary storage (not illustrated) to store the informationand the data. Next, the image generator 30 causes the image processor 32to generate medical images based on the received medical image data.

The image processor 32 receives instructions from the image generator 30and consecutively reads from the temporary storage, medical image datacorresponding to each phase and information indicating the tubularstructure as well as the core line corresponding to the data. Based onthe information, the image processor 32 subjects the medical image datathat has been simultaneously read to image processing while changing theposition (that is, the viewpoint position) of the camera along the coreline to generate medical images (that is, fly-through images)representing the tubular structure and the inside of the lumen from eachviewpoint position on the core line with regard to the each phase.

The image processor 32 respectively outputs the generated fly-throughimages corresponding to each phase to the display controller 50. Thedisplay controller 50 causes the display of the U/I60 to display thefly-through images corresponding to each phase that has been receivedfrom the image processor 32 in chronological order. Whereby, it becomespossible for the operator to designate, via the operation part, theposition of an observation object inside the tubular structure for eachtiming point while sequentially using the fly-through imagescorresponding to each timing point as a reference.

The U/I60 outputs information (that is, positional information)indicating the position (specifically, the position or the region insidethe tubular structure) of the observation object designated for eachtiming point to the viewpoint position-identifying part 31 via theoperation part. The viewpoint position-identifying part 31 identifiesthe coordinates indicated by the positional information designated foreach timing point as an object position corresponding to the timingpoint.

Based on the positional information regarding the object positioncorresponding to each timing point, the viewpoint position-identifyingpart 31 identifies the viewpoint position (that is, the one viewpointposition) for generating a fly-through image when viewing an observationobject for each timing point. Specifically, first, the viewpointposition-identifying part 31 reads medical image data corresponding tothe timing point of a processing object from the temporary storage.Next, as shown in FIG. 4A, the viewpoint position-identifying part 31identifies the core line R1 in the medical image data based on theinformation indicating the core line that has been linked to the medicalimage data viewpoint

Next, the viewpoint position-identifying part 31 identifies, as oneviewpoint position, the position P11 separated from the object positionP12 by a preliminarily determined distance L in a predetermineddirection (−z direction) along the core line R1.

Once the one viewpoint position P11 is identified, the viewpointposition-identifying part 31 outputs information indicating theviewpoint V11 when viewing the object position P12 from the identifiedone viewpoint position P11 and corresponding medical image data to theimage processor 32. The image processor 32 generates a medical image(that is, a fly-through image) based on the information indicating theviewpoint V11 as well as the medical image data and causes the imagestorage 40 to store the information and the data. As described, withregard to all timing points, the viewpoint position-identifying part 31identifies one viewpoint P11, generates a medical image when viewing theobject position P12 from the identified one viewpoint position P11,links the medical image to information indicating the timing pointcorresponding to the medical image data of the generation source, andcauses the image storage 40 to store the medical images and theinformation. As described, with regard to medical image data at aplurality of timing points corresponding to a predetermined examination,a series of medical images are generated and stored in the image storage40.

The display controller 50 reads a series of medical images correspondingto the prescribed examination from the image storage 40. Using theinformation indicating the timing point incidental to each of the readmedical images as a reference, the display controller 50 generates amotion image by arranging a series of medical images in chronologicalorder. The display controller 50 causes the display of the U/I60 todisplay the generated motion image.

As described thus far, in the medical image processing apparatuspertaining to Modified Example 1, the object position P12 is designatedby the operator with regard to medical image data corresponding to eachtiming point and, with regard to each timing point, one viewpointposition P11 separated from the object position P12 by a predetermineddistance L along the core line R1 is identified. With such aconfiguration, the distance between the object position P12 (or P13) andthe one viewpoint position P11 becomes even among each timing point.Thereafter, the medical image processing apparatus generates anddisplays a motion image by arranging a series of generated medicalimages in chronological order. Therefore, as in the medical imageprocessing apparatus in Embodiment 1, even when the position of anobservation object changes due to body movements, it becomes possible todisplay the observation object as a motion image while maintaining theobservation object in a predetermined size.

Embodiment 2

Next, a medical image processing apparatus pertaining to Embodiment 2 isdescribed. In the medical image processing apparatus pertaining toEmbodiment 1 and Modified Example 1, the object position P12 wasdesignated by the operator; however, in the present embodiment, theposition of tissues having form characteristics such as vocal cords,etc. is automatically detected as object position P12 by the medicalimage processing apparatus itself. Hereinafter, operations of themedical image processing apparatus pertaining to the present embodimentare described with reference to FIG. 5B, focusing on areas that aredifferent from Embodiment 1. FIG. 5B is a flow chart showing the seriesof operations of the medical image processing apparatus pertaining toEmbodiment 2.

(Step S21)

The structure extracting part 20 reads medical image data correspondingto a predetermined timing from medical image data of a plurality oftiming points corresponding to a predetermined examination. Thestructure extracting part 20 instructs the tubular structure-extractingpart 21 and the core line-extracting part 22 to identify a tubularstructure and a core line with respect to the read medical image data.The method of extracting the tubular structure and the core line withrespect to each medical image data is the same as Embodiment 1. Once thetubular structure and the core line are extracted, the structureextracting part 20 outputs information indicating the tubular structureand the core line as well as medical image data corresponding to theinformation to the image generator 30.

The image generator 30 receives medical image data to which theinformation indicating the tubular structure and the core line is linkedfrom the structure extracting part 20. The image generator 30 outputsthe information and the medical image data to the viewpointposition-identifying part 31.

(Step S22)

The viewpoint position-identifying part 31 receives the informationindicating the tubular structure and the core line as well as themedical image data, analyzes the information, and detects the formcharacteristics of an observation object (for example, vocal cords)preliminarily designated in the tubular structure. It should be notedthat the observation object (for example, the site of the vocal cords,small intestine, large intestine, etc.) may be designated by theoperator via the U/I60, or preliminarily determined information may alsobe stored in the apparatus. The viewpoint position-identifying part 31identifies the position of the detected form characteristics as theobject position P12.

(Step S23)

Next, based on the positional information of the object position P12,the viewpoint position-identifying part 31 identifies the viewpointposition (that is, the one viewpoint position P11) for generating afly-through image when viewing the observation object. Specifically,first, based on information indicating a core line linked to medicalimage data, as shown in FIG. 4A, the viewpoint position-identifying part31 identifies the core line R1 in the medical image data. Next, theviewpoint position-identifying part 31 identifies, as the one viewpointposition, a position P11 separated from the object position P12, by apreliminarily determined distance L in a predetermined direction (−zdirection) along the core line R1.

(Step S24)

Once the one viewpoint position P11 is identified, the viewpointposition-identifying part 31 outputs information indicating theviewpoint V11 when viewing the object position P12 from the identifiedone viewpoint position P11 and corresponding medical image data to theimage processor 32. The image processor 32 generates a medical image(that is, a fly-through image) based on the information indicating theviewpoint V11 and medical image data, links the medical image toinformation indicating the timing corresponding to the medical imagedata of the generation source, and causes the image storage 40 to storethe medical image and the information.

(Step S25)

With regard to all timing points, if the one viewpoint position P11 hasbeen identified but a corresponding medical image has not been generatedyet (Step S25, N), the image generator instructs the structureextracting part 20 to identify a tubular structure and a core lineregarding the medical image data of the following timing point. Asdescribed, with regard to the medical image data of a plurality oftiming points corresponding to a predetermined examination, a series ofmedical images are generated and stored in the image storage 40.

(Step S26)

With regard to all timing points, once the one viewpoint position P11has been identified and a series of medical images corresponding to apredetermined examination has not been stored (Step S25, Y), the displaycontroller 50 reads a series of medical images from the image storage40. Using information indicating the timing incidental to each of theread medical images as a reference, the display controller 50 generatesa motion image by arranging a series of medical images in chronologicalorder. The display controller 50 causes the display of the U/I60 todisplay the generated motion image.

It should be noted that in the above, the object position P12 isidentified based on information indicating a tubular structure; however,the method is not limited as long as the object position P12 isidentifiable. For example, as in Embodiment 1, by generating afly-through image, based on this, the form characteristics may bedetected. Moreover, the form characteristics may also be detected basedon the sagittal images shown in FIG. 2A or in FIG. 3A or images fromother directions.

As described thus far, with regard to each timing point, the medicalimage processing apparatus pertaining to the present embodiment analyzesinformation based on medical image data (for example, informationindicating a tubular structure), detects the form characteristics, andidentifies the object position P12. Thereafter, the medical imageprocessing apparatus generates a medical image by identifying the oneviewpoint position P11 such that the distance between the objectposition P12 (or P13) and the one viewpoint position P11 becomes evenamong each timing point. Thereby, even when the position of anobservation object changes due to body movements, the medical imageprocessing apparatus itself automatically detects the position of theobservation object, making it possible to display the observation objectin a predetermined size in the medical image.

Modified Example 2

Next, a medical image processing apparatus pertaining to ModifiedExample 2 is described. In the previous embodiments and modifiedexamples, an example of displaying a medical image from a viewpoint V11that is separated from the object position P12 by a preliminarilydetermined distance L in the preliminarily predetermined direction (−zdirection) along the core line R1 was described. In the medical imageprocessing apparatus pertaining to Modified Example 2, in addition tothe medical image from this viewpoint V11, a medical image from aviewpoint V21 located on the opposite side from the viewpoint V11 isdisplayed such that the sizes of an observation object among a pluralityof timing points become the same. Hereinafter, the configuration of themedical image processing apparatus pertaining to Modified Example 2 isdescribed with reference to FIG. 6, focusing on the operations of theviewpoint position-identifying part 31 different from the previouslydescribed embodiments and modified examples. FIG. 6 is a drawing fordescribing a method of identifying the one viewpoint position in themedical image processing apparatus pertaining to Modified Example 2.

The viewpoint position-identifying part 31 first identifies the objectposition P12 and the one viewpoint position P11. The method ofidentifying these is the same as in the previously described embodimentsand modified examples. It should be noted that in case of medical imagedata corresponding to another timing in Embodiment 1, the one viewpointposition P11 of a medical image matched with a standard medical image isidentified and a position separated from the one viewpoint position P11by the distance L in the direction to which a viewpoint is facing alongthe core line R1 just has to be identified as the object position P12.

Once the object position P12 and the one viewpoint position P11 areidentified, based on the object position P12, the viewpointposition-identifying part 31 identifies, as another viewpoint positionP21, a position P21 separated by the distance L in the direction (thatis,) on the opposite side from the viewpoint position P11 along the coreline R1. Once the one viewpoint position P11 and the one viewpointposition P21 are identified, the viewpoint position-identifying part 31outputs information indicating the viewpoint V11 when viewing the objectposition P12 from the identified one viewpoint position P11, informationindicating the viewpoint V21 when viewing the object position P12 fromthe one viewpoint position P21, and the corresponding medical image datato the image processor 32. Based on the information indicating theviewpoints V11 and V21 and the medical image data, the image processor32 generates medical images with regard to both viewpoints V11 and V21(that is, the fly-through images), respectively links the each image tothe information indicating the timing points corresponding to themedical image data of the generation sources, and causes the imagestorage 40 to store the medical images and the information. FIG. 7A andFIG. 7B show one example of generated medical images. The medical imageD122 shown in FIG. 7A is a fly-through image of a case in which theobject position P12 is displayed from the viewpoint position P11, thatis, showing a medical image based on the viewpoint V11. Furthermore, themedical image D123 shown in FIG. 7B is a fly-through image of a case inwhich the object position P12 is displayed from the viewpoint positionP21, that is, showing a medical image based on the viewpoint V21. Asdescribed, with the object position P12 as a reference point, thedistance to the one viewpoint position P11 and the distance to the oneviewpoint position P21 become the same (that is, the distance L);consequently, as shown in FIG. 7A and FIG. 7B, the sizes of theobservation object (that is, the vocal cords) become the same betweenthe two images. As described, with regard to medical image data of aplurality of timing points corresponding to a predetermined examination,a series of medical images are generated and stored in the image storage40.

When a series of medical images corresponding to a predeterminedexamination are stored in the image storage 40, the display controller50 distinguishes and reads medical images based on the viewpoint V11 andmedical images based on the viewpoint V21 from the image storage 40. Thedisplay controller 50 uses information indicating the timing incidentalto each read medical image, arranges a series of medical images inchronological order, and generates motion images. Thereby, a motionimage based on the viewpoint V11 and a motion image based on theviewpoint V21 are generated. The display controller 50 causes thedisplay of the UI/60 to display the generated motion images. It shouldbe noted that, subsequently, the display controller 50 may also causethe display to display each motion image by matching the timing point ofthe motion picture based on the viewpoint V11 and the timing of themotion picture based on the viewpoint V21.

It should be noted that in the above, an example of identifying the oneviewpoint positions P11 and P21 separated by the distance L along thecore line R1 based on the object position P12 was described; however,each one viewpoint position does not necessarily have to be along thecore line R1 as long as the position is separated from the objectposition P12 by the distance L.

Furthermore, the display controller 50 may also display medical imagesby inverting left to right either the medical image (or motion image)based on the viewpoint V11 or the medical image (or motion image) basedon the viewpoint V21. Such a display aspect is described specificallywith reference to FIG. 8A through 8D. The image D30 shown in FIG. 8A isone example of such a display aspect, in which with respect to medicalimage data obtained by imaging the large intestine, the viewpoint V11and the viewpoint V21 are identified as previously described and anexample displaying a medical image from each viewpoint is shown. Themedical image D31 in FIG. 9A corresponds to the viewpoint V11 while themedical image D322 is an inverted display of a medical image D321corresponding to the viewpoint V21.

Herein, FIG. 8B and FIG. 8C are used as references. FIG. 8B shows amedical image D31 corresponding to the viewpoint V11. FIG. 8C shows amedical image D321 corresponding to the viewpoint V21. Herein, in bothmedical images, if the left direction is “−x direction” and the right is“+x direction”, the internal wall displayed on the +x direction side ofthe medical image D31 is displayed on the −x direction side on themedical image D321 side. For this, when these medical images aredisplayed together, it is difficult to intuitively discover which ofeither the left or the right portion in each medical image correspondsto which part of the other medical image.

For this reason, in the display aspect shown in FIG. 8A, the medicalimage D322 which is a left to right inversion of the medical image D321is displayed together with the medical image D31. Herein, FIG. 8D isused as a reference. FIG. 8D is a drawing explaining the display aspectshown in FIG. 8A. As described, by displaying the medical image D322which was a left to right inversion together with the medical image D31as shown in FIG. 8A, for example, a portion corresponding to the +xdirection in the medical image D31 from the viewpoint V11 and the −xdirection in medical images (that is, medical images D321 and 322)corresponding to the viewpoint V21 are displayed in the same direction(that is, the right side). Therefore, it becomes easier to intuitivelydiscover which of either the left or the right portion in one of themedical images corresponds to which part of the other medical image.

As described thus far, the medical image processing apparatus pertainingto Modified Example 2 generates, at each timing point, medical images inwhich an observation object is displayed from a plurality of directions.Subsequently, the position of a viewpoint to generate each medical image(that is, the one viewpoint positions P11 and P21) is set at a locationseparated by an equal distance L, when the position of the observationobject (that is, object position P12) is a reference point. Asdescribed, with regard to each timing point, the viewpoints V11 and V21are identified to generate medical images based on each viewpoint.Thereby, it becomes possible to display medical images from a pluralityof directions such that the sizes of the observation object become thesame and, even in the case of position changes of the observation objectdue to body movements, it is possible to display the observation objectin a motion image while maintaining the observation object in apredetermined size.

Modified Example 3

Next, a medical image processing apparatus pertaining to ModifiedExample 3 is described. In the previously described embodiments and themodified examples, an example of displaying a medical image from theviewpoint V11 separated from the object position P12 by a preliminarilydetermined distance L along the core line R1 was described. However, forareas in which a tubular structure has a rapid curve such as the largeintestine or the aorta, after one viewpoint position is determined alongthe core line, because the wall surface of the tubular structureinterposes between a viewpoint and an observation object, it issometimes impossible to view the observation object from the viewpoint.Herein, FIG. 12A is used as a reference. FIG. 12A is a drawingdescribing a method of identifying the one viewpoint position pertainingto Modified Example 3 and shows an outline of a large intestine. The oneviewpoint position P51 and the object position P52 in FIG. 12Arespectively correspond to the one viewpoint position P51 and the objectposition P52 in FIG. 11A. When the viewpoint V11 is provided at the oneviewpoint position P11 along the core line R1 to display a fly-throughimage when viewing the object position P52, the region indicated by M52is blocked by the intestinal wall and cannot be observed from theviewpoint V11. Therefore, in the medical image processing apparatuspertaining to Modified Example 3, in such a case, for example, aposition separated from the object position by the distance L in apredetermined direction is identified as the one viewpoint positionwithout limiting the core line R1. Hereinafter, the method ofidentifying the one viewpoint position by the medical image processingapparatus pertaining to Modified Example 3 is described focusing on anareas that are different from other embodiments or modified examples bytaking an example of a case with a large intestine as shown in FIG. 12A.

The structure extracting part 20 respectively reads the medical imagedata at a plurality of timing points corresponding to a predeterminedexamination. The structure-extracting part 20 instructs the tubularstructure-extracting part 21 and the core line-extracting part 22 toidentify a tubular structure and a core line with respect to the readmedical image data. Thereby, a tubular structure and a core line R51 areidentified with regard to each image data. The method of extracting thetubular structure and the core line with respect to each piece ofmedical image data is the same as the previously described embodimentsand modified examples. Once the tubular structure and the core line R51are extracted, the structure extracting part 20 outputs informationindicating the tubular structure as well as the core line R51 andmedical image data corresponding to the information to the imagegenerator 30.

The image generator 30 receives medical image data to which theinformation indicating the tubular structure and the core line R51 islinked from the structure extracting part 20. The image generator 30outputs the information and the medical image data to the viewpointposition-identifying part 31.

Once the information indicating the tubular structure and the core lineR51 as well as the medical image data are received, the viewpointposition-identifying part 31 analyses the information, verifies theobservation object, and identifies an object position P52. The method ofidentifying the object position P52 is the same as in the previouslydescribed embodiments and modified examples.

Next, based on the positional information of the object position P52,the viewpoint position-identifying part 31 identifies the viewpointposition (that is, the one viewpoint position) for generating afly-through image when viewing the observation object. Specifically, asshown in FIG. 12A, the viewpoint position-identifying part 31 identifiesa position separated from the object position P52 by the distance L in apredetermined direction as the one viewpoint position P51 a. Then, thedirection for identifying the one viewpoint position P51 a may be, forexample, the direction of the tangent line R51 a of the core line R51 atthe object position P52 or the direction of a normal line of across-section formed by cutting the tubular structure at the objectposition P52.

Furthermore, the viewpoint position-identifying part 31, firstdetermines the one viewpoint position P51 along the core line R51 andanalyses, based on the information indicating the tubular structure,whether the observation object may be viewed from the one viewpointposition P51, that is, whether or not an obstacle (for example, the wallsurface of the tubular structure) is present between the one viewpointposition P51 and the object position P52. Thereafter, if the observationobject cannot be viewed from the one viewpoint position P51, asdescribed above, the one viewpoint position P51 a may be identified. Itshould be noted that in this case, needless to say, the method ofidentifying (identifying either one viewpoint position P51 or P51 a) oneviewpoint position should be consistent with regard to all image data.

Once the one viewpoint position P51 a is identified, the viewpointposition-identifying part 31 outputs information indicating theviewpoint V51 a when viewing the object position P52 from the identifiedone viewpoint position P51 a and corresponding medical image data to theimage processor 32. Based on the information indicating the viewpointV51A and the medical image data, the image processor 32 generates amedical image (that is, a fly-through image), links the images toinformation indicating a timing point corresponding to medical imagedata of the generation source, and stores the images and the informationin the image storage 40. FIG. 12B is one example of the medical imageD522 (fly-through image) when viewing the object position P52 from theviewpoint V51 a. P52 in FIG. 12B corresponds to the object position P52in FIG. 12A. Furthermore, M52 corresponds to the portion M52 in FIG.52A. As described, by providing the viewpoint V51 a instead of the oneviewpoint position P51 (ref. FIG. 12A), it becomes possible to obtainthe medical image D522 when viewing the region M52 that is difficult tobe observed from the one viewpoint position P51 blocked by the wallsurface of the tubular structure.

The processes from hereinafter are the same as in the other embodimentsand modified examples. That is, once the one viewpoint position P51 a isidentified with regard to all timing points and a series of medicalimages corresponding to a predetermined examination are stored in theimage storage 40, the display controller 50 reads a series of medicalimages from the image storage 40. The display controller 50 usesinformation indicating the timing point incidental to each read medicalimage as a reference, arranges a series of medical images inchronological order, and generates a motion image. The displaycontroller 50 causes the display of the U/I60 to display the generatedmotion image.

As described thus far, the medical image processing apparatus pertainingto Modified Example 3 identifies the position separated by the distanceL from the object position P52 in a predetermined direction as the oneviewpoint position P51 a. Thereby, even if an observation object cannotbe viewed from the one viewpoint position on the core line R51 such as aportion with a rapidly curved tubular structure like a large intestineor an aorta, it becomes possible to generate a medical image whenviewing the observation object and obtain the same action effects as inthe above embodiments and modified examples.

Modified Example 4

Next, the medical image processing apparatus pertaining to ModifiedExample 4 is described. An example of identifying the one viewpointposition within a tubular structure was described in Modified Example 3.However, if the tubular structure is further bent in comparison to theexample shown in Modified Example 3, sometimes a position separated froman object position by the distance L ends up being outside the tubularstructure. Such a situation is described specifically with reference toFIG. 13A. FIG. 13A is an example schematically showing the structure ofthe aorta shown in FIG. 10A. An object position P42 in FIG. 13A isequivalent to the object position P42 in FIG. 10A. Moreover, the oneviewpoint position P41 is equivalent to the one viewpoint position P41in FIG. 10A and, R41 is equivalent to the core line R41 in FIG. 10A.Furthermore, M41 and M42 in FIG. 13A show a wall surface of the tubularstructure.

A viewpoint V41 is set as the one viewpoint position P41 to generate afly-through image when viewing the object position P42. In this case, aregion M421 on the wall surface M42 on the inner circumference side inthe tubular structure is blocked by the wall surface M42 on the upstreamside of the region 421 and is difficult to be observed from theviewpoint V41. On the other hand, as shown in Modified Example 3, aposition separated from the object position P42 by the distance L in thetangent line direction of the core line R41 is presumed to be the oneviewpoint position P41 a. In this case, as shown in FIG. 13A, the oneviewpoint position P41 a ends up being outside the tubular structure.Therefore, due to the blockage by the wall surface M41 of the outercircumference of the tubular structure, it becomes difficult to view theobject position P42 from the viewpoint V41 a provided at the oneviewpoint position P41 a.

Incidentally, as shown in FIG. 13A, the medical image processingapparatus pertaining to Modified Example 4 makes it possible to set theviewpoint V41 a at the one viewpoint position P41 a outside the tubularstructure and generates a medical image when viewing the object positionP42 by not allowing a region M411 to be displayed which blocks the fieldof view of the viewpoint V41 in the wall surface of the tubularstructure. Hereinafter, operations of the medical image processingapparatus pertaining to Modified Example 4 are described focusing onareas that are different from Modified Example 3 by taking the exampleof the aorta that is shown in FIG. 13A and FIG. 13B. FIG. 13B is adrawing explaining the method of identifying the one viewpoint positionpertaining to Modified Example 4 and the outline of the heart and theaorta are shown therein.

The structure extracting part 20 respectively reads medical image dataat a plurality of timing points corresponding to a predeterminedexamination. The structure extracting part 20 instructs the tubularstructure-extracting part 21 and the core line-extracting part 22 toidentify a tubular structure and a core line with respect to the readmedical image data. Thereby, a tubular structure and a core line R41 areidentified with regard to each piece of image data. The method ofextracting the tubular structure and the core line with respect to eachmedical image data is the same as in the previously describedembodiments and modified examples. Once the tubular structure and thecore line R41 are extracted, the structure extracting part 20 outputsinformation indicating the tubular structure as well as the core lineR41 and medical image data corresponding to the information to the imagegenerator 30.

The image generator 30 receives medical image data to which theinformation indicating the tubular structure and the core line R41 islinked from the structure extracting part 20. The image generator 30outputs the information and the medical image data to the viewpointposition-identifying part 31.

Once the information indicating the tubular structure and the core lineR41 as well as the medical image data are received, the viewpointposition-identifying part 31 analyses the information, verifies theobservation object, and identifies the object position P42. The methodof identifying the object position P42 is the same as the previouslydescribed embodiments and modified examples.

Next, based on the positional information of the object position P42,the viewpoint position-identifying part 31 identifies the viewpointposition (that is, the one viewpoint position) for generating afly-through image when viewing the observation object. Specifically, asshown in FIG. 13A and FIG. 13B, the viewpoint position-identifying part31 identifies a position separated from the object position P42 by thedistance L in a predetermined direction as the one viewpoint positionP41 a. Then, the direction for identifying the one viewpoint positionP41 a may be, as in Modified Example 3, the direction of the tangentline R41 a of the core line R41 at the object position P42 or thedirection of a normal line of a cross-section formed by cutting thetubular structure at the object position P42. Then, as shown in FIG. 13Aor FIG. 13B, the one viewpoint position P41 a is presumed to be locatedoutside the tubular structure.

It should be noted that the viewpoint position-identifying part 31 firstdetermines the one viewpoint position P41 along the core line R41 andanalyses, based on the information indicating the tubular structure,whether the observation object may be viewed from the one viewpointposition P41, that is, whether or not an obstacle (for example, the wallsurface of a tubular structure) is present between the one viewpointposition P41 and the object position P42. Thereafter, if the observationobject cannot be viewed from the one viewpoint position P41, asdescribed above, the one viewpoint position P41 a may be identified. Itshould be noted that in this case, needless to say, the method ofidentifying (identifying which of one viewpoint position either P41 orP41 a is to be identified) the one viewpoint position should beconsistent with regard to each piece of image data.

Once the one viewpoint position P41 a is identified, first, theviewpoint position-identifying part 31 identifies the viewpoint V41 awhen viewing the object position P42 from the one viewpoint position P41a. Furthermore, the viewpoint position-identifying part 31 compares theinformation indicating a tubular structure and the coordinates of theone viewpoint position P41 a and determines if the position is present,whether inside or outside the tubular structure. As shown in FIG. 13Aand FIG. 13B, if the coordinates of the one viewpoint position P41 a endup being outside the tubular structure, based on the coordinates of theone viewpoint position P41 a, the field of view angle of the viewpointV41 a, and information indicating the tubular structure, the viewpointposition-identifying part 31 identifies a region M411 overlapping thefield of view of the viewpoint V41 a in the wall surface of the tubularstructure. That is, when viewing the object position P42 from theviewpoint V41 a, the region M411 becomes an area that blocks the fieldof vision. The viewpoint position-identifying part 31 outputsinformation indicating the identified viewpoint V41 a, informationindicating the region M411, and medical image data correspondingthereto, to the image processor 32. It should be noted that operationsfor cases in which the coordinates of the one viewpoint position P41 aend up being inside the tubular structure are the same as in ModifiedExample 3, including the operations of the image processor 32 that aredescribed later.

Based on the information indicating the viewpoint V41 a and the medicalimage data, the image processor 32 generates medical images (that is,fly-through images). Then, based on the information indicating theregion M411, a portion equivalent to the region M411 in the wall surfaceof the tubular structure is not displayed by the image processor 32.FIG. 13C shows one example of a medical image D422 when viewing theobject position P42 inside the tubular structure from the viewpoint V41a located outside the tubular structure. As shown in FIG. 13C, by notshowing the region M411 interposing between the viewpoint V41 a and theobject position P42 in the wall surface of the tubular structure, itbecomes possible to view the object position P42 from the viewpoint V41a located outside the tubular structure. The image processor 32 linksinformation indicating a timing point corresponding to the medical imagedata of the generation source to the generated medical image and causesthe image storage 40 to store the images and information.

The processes hereinafter are the same as other embodiments and modifiedexamples. That is, once the one viewpoint position P41 a is identifiedwith regard to all timing points and a series of medical imagescorresponding to a predetermined examination are stored in the imagestorage 40, the display controller 50 reads a series of medical imagesfrom the image storage 40. The display controller 50 uses informationindicating the timing point incidental to each read medical image as areference, arranges a series of medical images in chronological order,and generates a motion image. The display controller 50 causes thedisplay of the U/I60 to display the generated motion image.

As described thus far, if one viewpoint position P41 a is locatedoutside the tubular structure, the medical image processing apparatuspertaining to Modified Example 4 identifies a region M411 that blocksthe field of vision from the viewpoint V41 a set at the one viewpointposition P41 a such that it is not displayed. Thereby, even if the oneviewpoint position P41 a is located outside the tubular structure, itbecomes possible to generate medical images when viewing an observationobject and obtain the same action effects as in the above embodimentsand modified examples.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel systems described herein maybe embodied in a variety of their forms; furthermore, various omissions,substitutions and changes in the form of the systems described hereinmay be made without departing from the spirit of the inventions. Theaccompanying claims and their equivalents are intended to cover suchforms or modifications as would fall within the scope and spirit of theinventions.

What is claimed is:
 1. A medical image processing apparatus, comprising:an image data storage that stores a plurality of medical image dataobtained by imaging inside of a subject at each of a plurality ofpredetermined timing points, a structure identifying part configured toidentify a tubular structure inside the subject and a core line in anaxial direction of the tubular structure based on the medical imagedata, an image generator configured to designate a position of apredetermined observation object in the tubular structure for each ofthe medical image data, to designate a viewpoint position at a constantdistance from the position of the redetermined observation objectdesignated for each of the medical image data along the core line, andto generate medical images representing the inside of the tubularstructure when viewing the predetermined observation object from theviewpoint position at the constant distance from the predeterminedobservation object inside the tubular structure based on the medicalimage data corresponding to the timing points, a display, and a displaycontroller configured to cause the display to display the medical imagesgenerated for each of the medical image data corresponding to each ofthe timing points.
 2. The medical image processing apparatus accordingto claim 1, wherein the image generator is configured to, in response todesignation of the position of the predetermined observation object foreach of the medical image data corresponding to each of the timingpoints, identify the viewpoint position corresponding to the constantdistance for each designated position of the observation object.
 3. Themedical image processing apparatus according to claim 1, wherein, theimage generator is configured to, in response to designation of theposition of the predetermined observation object for medical image datacorresponding to a predetermined timing point, detect an observationobject having the same form characteristics as those of thepredetermined observation object for each of the medical image data ateach of the timing points, to identify a position at which the formcharacteristics are detected as a position of the observation object ineach of the medical image data, and further to identify a positionseparated from the position of the observation object by the constantdistance as the viewpoint position.
 4. The medical image processingapparatus according to claim 1, wherein, for each of the timing points,the image generator is configured to identify another viewpoint positionlocated on the opposite side from the viewpoint position along the coreline from the position of the observation object, and respectivelygenerates the medical images viewing the position of the observationobject with regard to the viewpoint position and the another viewpointposition, and, for each of the timing points, the display controller isconfigured to cause the display to sequentially display the medicalimages respectively generated with regard to the viewpoint position andthe another viewpoint position corresponding to the timing point.
 5. Themedical image processing apparatus according to claim 4, wherein, amongthe medical images respectively generated with regard to the viewpointposition and the another viewpoint position, the display controller isconfigured to invert one of the medical images left to right and causesthe display to display the image.
 6. The medical image processingapparatus according to claim 1, wherein the image generator isconfigured to designate the observation object based on formcharacteristics in the tubular structure with respect to medical imagedata corresponding to each of the timing points.
 7. A medical imageprocessing apparatus, comprising: an image data storage that stores aplurality of medical image data obtained by imaging inside of a subjectat each of a plurality of timing points, a structure identifying partconfigured to identify a tubular structure inside the subject and a coreline in an axial direction of the tubular structure based on the medicalimage data, an image generator configured to designate a first positionof a predetermined observation object in the tubular structure withrespect to first medical image data corresponding to a predeterminedtiming point, specify a first viewpoint position at a predetermineddistance from the observation object based on the first medical imagedata, generate a medical image when the observation object is viewedfrom the first viewpoint position as a reference medical image, withrespect to second medical image data corresponding to another timingpoint different from the predetermined timing point, designate a secondposition of the observation object at the other timing point, specify asecond viewpoint position at a predetermined distance from the secondposition, and generate a medical image when the observation object isviewed from the second viewpoint position specified, a display, and adisplay controller configured to cause the display to display thereference medical image and the medical image generated at thepredetermined timing point and the other timing point.
 8. The medicalimage processing apparatus according to claim 7, wherein, for each ofthe timing points, the image generator is configured to identify anotherviewpoint position located on the opposite side from the first viewpointposition and the second viewpoint position along the core line from theposition of the observation object, and generates the medical imageviewing the position of the observation object with regard to each ofthe first viewpoint position, the second viewpoint position, and theanother viewpoint position, and, for each of the timing points, thedisplay controller causes the display to sequentially display themedical image generated with regard to each of the first viewpointposition, the second viewpoint position, and the another viewpointposition corresponding to the timing point.
 9. The medical imageprocessing apparatus according to claim 8, wherein among medical imagesgenerated with regard to the first viewpoint position, the secondviewpoint position, and the another viewpoint position, the displaycontroller is configured to invert one of the medical images left toright and causes the display to display the image.
 10. The medical imageprocessing apparatus according to claim 7, wherein, the image generatoris configured to designate the second position of the observation objectwith respect to the second medical image data corresponding to theanother timing point different from the predetermined timing point, andgenerate a second medical image based on the second medical image datawhile changing a viewpoint position along the core line in the secondmedical image data, and the image generator is further configured to seta viewpoint position, where size of the second medical image correspondsto size of a first medical image based on the first medical image data,as the second viewpoint position, and designate the second medical imagein the second viewpoint position.
 11. The medical image processingapparatus according to claim 7, wherein in response to designation of aposition of the observation object with respect to medical image datacorresponding to each of the timing points, the image generatordesignates a viewpoint position corresponding to the predetermineddistance for the position of the observation object designated.
 12. Themedical image processing apparatus according to claim 7, wherein theimage generator is configured to designate the observation object basedon form characteristics in the tubular structure with respect to medicalimage data corresponding to each of the timing points.